In recent years, devices capable of performing authentication on a device of a power supply target such as a power supply device for a vehicle, for example, an electric vehicle (EV), and selectively supplying the device of the power supply target with power according to an authentication result have been released. In addition, a technique of performing a billing process according to an amount of supplied electric power has been also developed. As a technique of performing billing for every local area network (LAN) on an amount of electric power supplied to LAN device, for example, there is a technique discussed in Patent Literature 1.